Method and apparatus for hydrazine decomposition



March 29, 1960 I o. J. PLESCIA ETAL 2,930,184 METHOD AND APPARATUS FOR HYDRAZINE DECOMPOSITION 34 5mm May 13, 1949 HYDRAZINE SUPPLY FlG.l

FIG.2

INVENTORS OTTO J. PLESCIA BY RUSSELL M. MANTELL FREDERICK J. MARTIN ATTORN YS Otto J. 'Plescia', New York, N.Y., Russell M. Marten,

' Newark, N.J., and Frederick J; Martin, Staten Isiland,

N.Y;, assignors to The M. W. Kellogg Compan'ygJersey y NJ a corporation ofiDelaware Application May. 1s,;1 9.49,se;a1- o. 93,006. 20 Claims; (or. Gil-35.4)

Thisninvention relates; to; the. decomposition of hydrazine; Inoneaspect, thisiinvention. r'elatesfltoa method and apparatus for the decomposition. ofihydrazineas a gas generant. Morespecifidallydh this aspect, the invention:

' relates to an improved method and apparatus for the catalytic decomposition of hydrazine asza. gas generant. The use of hydrazine as-a gascgenerant. for. turbines,

- supersonic-vehicles, guided missiles; rockets and thelike, has beengfound highly preferably over that of hydrogen peroxide, which has heretofore": been; catalytically. de-

composed 'for such purposes; In this. respect,.,the use U i sw s ofi hydrazine asr a gas generant is-Qparticularly attractive by, reasonof its:significantly greater performancegefficiency, and its greater stability. which eliminates storage.

and transportation difficulties normally encountered. in

*the handling of hydrogen peroxide as a gas generant.

' It:is, ther efore,1an object of the'present, inventionito provide for an improved method for the decomposition (if-hydrazine.

Another object of the invention, is a; provide. ro'ran.

improvedmethod and apparatus for the xdecomposition .ofhydra'zine; I p A; further. object of the invention is to provide for an improvedmethod and apparatus for the'catalytic de composition of hydrazine as a gas generant.

Furtherobjects and advantages jinherent in the invention will be apparent. torthose skilled in the art the following moredetailed' disclosure;

In the drawing: w ,7

The accompanying drawing. illustrates, partly in crosssection,.'elevational views of apparatus for carrying out from 1 V avoided.

catalytic decomposition oi hydrazine as agas generant,f'-

either. in a single reaction chamber (Figure l) or..in two reaction chambers (Figure, 2.). These hydrazine gas'generators of thedrawingare capable of developing an 1 average chamber pressure of approximately 275 1 pounds per square inch absolute or higher.

The principal elements of the single reaction chamber of Figure 1 indie drawingcomprise a shell 10, aiheader or bonnet12 having a nozzle 1401' "other conventional means foriintroducing hydrazine into the-reaction chamher, a first plurality of foraminous metalmembranes 16,.

a second plurality of foraminous metal membranes 18, and an exhaust nozzle 201 -,.i

- Shell 19 in Figure 1 is a conventional cylinder con- I structed of inch stainless steel, approximately 10 /2 inches in length and having an inside diameter of 'ap- Headerv '12 is a cylindrical sec tion, having'a fiat'or elliptical end, through which noz-i zlel4 for. introducing hydrazine is' inserted! This header proximately 3, inches.

is 'constructedfof inch stainless steel andis connected to channel section 22 by conventional means known to those skilled in theart, such as by Welding; bolting, threadingor clamping.- QChannel 22 comprises a flanged cylindrical shell-constructed of /8 inch stainless steel,

'Thelower side-of channel 22 is connected in a' suitable manner to the upper portion of shell 10.

The membranes represented by numeral: l6-comprise at-leastseveral?inchesjin order'toobtain sati'stactory hy actionschamber, has-"an: upper enlarged sectionyof abut 3 inches'inside diameter and' a' lower restricted secti'o" 'in contact-with the lowest screen comprising niembr'a "comprises 'a plurality of. metal'screens of copper, iron,-

brass, stainless steel, or other metalsurface, which are; j superimposed on alternate layers: of; granular" catalyst particles, represented "by, numeral24, and which are posi t1oned..in the hollow spaces;between the'metal screen's; these spaces-being. represented by'f-numer'al 26.- The catalyst composition: willrbe fully 'discussed hereinafter? during. the description of'the operation of the-apparatus;-

The'depth or total thickness of the above-mentioned ab ternate layersof screens and catalyst will vary with the capacity requirements of the reaction chamber, although it is preferred that the granular catalyst particlesbe posi tioned. within hollow spaces '26"bet'ween alternate layers" a of the metal screens to a thicknesszof"approximately A inch. At this point it will be noted that' while the above-- mentioned first plurality. of fforaminous rri'e'tal membranes is. represented in theiprefer'red form of the appar'atus", comprisingthesingle reaction ,ch'amberof Figurel, as a series of metal screens-superimposed on"alternate"layers" of granular catalyst particles, it is possible iii'another modification of the apparatus, if so'des'ir ed; to liav -only I a single metal screen or foraminous metal -mrnbrane" positioned across the upper portion of the reaction chameher, with a single layer of catalyst b'ed po sitioned 'on the screen; However,- the modification represented 'in Figure l in the drawing is preferred, by reason "that in employ ingJ-thearrangement asshowmpos'sible fusion or sinte ri mg of the catalyst and clogging of 'the met-a1 screen is The-'membranes represented by numeral 18 in Figure '1 also comprise a plurality of fora'minou s metal mem branes similar in construction to membranes 16l- Membranes 18 preferably, comprise-aplu'rality of"s'uperiniiposed metal: screens positioned transversely"across the .thethick'ness of a single screen to 'sucha thicklies's of screen layers that the-uppermost'iscreen layer is almosfi 16, it is-preferred thatsmembra'nes 18 havea depth' 0* .dra'zine decomposition: The" hydrazine ydecemppsaibn takes place for the-most part Within' the area coiifine metalsscreens l -astwillbe fully discussed herei'naf r during the de'scription' of theoperation of the apparatus} MembraneslG-and 18 may be of anysuitable nlesh and preferably a 20'to imesh' and- .01'6"inch,wirei Nozzle '20; which may bean exhaust nozzle, verituri,

or anyothermeans for conductin'g gasesfrom.the re'-- ofaboutMtainch'inside diametefi This nozzle or=oth outlet means may'be faste'ned' to'the outlet end of sliell '10, by threading-welding; bolting of clamping; known to those skilled in the art, and may be made ofari'y suitable metallic material such as stainlessfsteel, copper, brassor'iron.

Numeral 14 in Figurel indicates a nozzle or any" conventional means" forintrodu'cing. hydrazine into the reaction chamber, and preferably may be'an" adjustablej atomizer nozzle, threaded or welded into header" I Z and met-a1, membranes positioned V I a main decomposition or reaction chamber.

extending into the reaction chamber. This nozzle may be constructed of any suitable material such as stainless steel, copper, brass or iron.

A valved-conduit 28 is attached to nozzle 14 for the introduction of hydrazine into the reaction chamber, the rate of flow being controlled by valve 30 in conduit 28. Conventional pumping apparatus, represented by pump 32, is connected to conduit 28 for pumping a supply of hydrazine from a suitable storage supply vessel 34 which is attached to pump 32 through conduit 36. Storage vessel' 34 and conduits 28 and 36 are constructed of any suitable material such as inch stainless steel, or iron, the aforementioned conduits having an inside diameter of approximately 4 inch. Nu-

meral 38 indicates a break in the drawing and thus the apparatus is not shown in its true length.

- In another embodiment of the apparatus of the invention, the two-reaction chamber apparatus of Figure 2 in the drawing, comprises an initiator chamber and pal elements of the initiator chamber comprise a shell 40, a header or bonnet 42 having a nozzle 44 or other conventional means for'introducing hydrazine into the initiator chamber, a truncated conical screen 46, a foraminous metal membrane 48 and a conduit for exhaust gases 50. The principal elements of the main reaction chamber comprise a shell 52, a header or bonnet 54 having a nozzle 56 or other conventional means for introducing hydrazine into the main reaction chamber, a plurality of foraminous metal membranes 58 and an exhaust nozzle 60.

Shell '40, in the initiator chamber in Figure 2, is a conventional shell constructed of inch stainless steel,

similar to shell in Figure l, and approximately 4 inches in length having an inside diameter of approximately 1% inches. Header 42 is a cylindrical section, which may be similar in construction to header 12 in Figure 1, and through which nozzle 44 for introducing hydrazine into the initiator chamber is inserted. This header is connected to shell 40 by conventional means known to those skilled in the art, such as by welding, threading, or clamping.

Membrane 46 is preferably a truncated conical metal screen positioned longitudinally within the initiator chamber. This screen is fastened at its base to the walls of shell 40 directly below header 42, by any suitable conventional means such as welding or bolting, so that a hollow space 62 is formed between the walls of shell 40 and the screen. Screen 46 is preferably a metal screen of copper, iron, brass, stainless steel or other metal surface. Numeral 64 indicates granular catalyst particles positioned in hollow space 62 between the walls of shell 40 and screen 46. Membrane 48 is also a The princiforaminous metal membrane or screen similar in construction to screen 46. Membrane 48 is' positioned transversely across the outlet end of the initiator chamber and; is attached to the walls of shell 40 by any conventional fastening means. This membrane is preferably slightly raised from the outlet end of'the initiator chamber for the purpose of allowing free flow of gases from the initiator chamber.

A third membrane or metal screenv 66, similar in construction to screen 48, is positioned transversely across the inlet end of the initiator chamber between header 42 and the base of screen 46. This membrane is fastened to the inner walls of shell 40 by any suitable conventional means such as welding or bolting The hydrazine decomposition takes place for the most part, in the initiator chamber, within the area confined by metal screens 46 and 48.

Conduit 50 is attached to channel 68, the latter comprising a flanged cylindrical shell constructed of inch stainless steel which is attached to the walls of shell 40. Conduit 50 is preferably centered in channel 68 for the eflicient introduction of exhaust gases from the initiator chamber to the main reaction chamber. Con- 72,930,134 V v a p v duit 50 is approximately 1 inches in length, and constructed of stainless steel having an inside diameter of approximately inch. It is preferable that this conduit be as short as possible in order to minimize cooling of the hot reactor gases which are transferred through this conduit to the main reaction chamber, as will be fully discussed hereinafter during the description of the operation-of theapparatus. Numeral 44 indicates a nozzle or any-conventional means for introducing hydrazine into the initiator chamber, preferably an ad-' justable atomizer nozzle similar to atomizer nozzle 14 in Figure l, and is threaded or welded into header 42 and extends into the initiator chamber.

Shell 52 in the main reaction chamber in Figure 2, is a conventional cylinder similar to shell 10 in Figure 1, constructed of inch stainless steel, approximately 10 /2 inches in length and having an inside diameter of approximately 3 inches. Header 54 is a cylindrical section, similar to header 12 in Figure 1, having a-flat or elliptical end, through which nozzle 56 for introducing hydrazine is inserted. This header is constructed of inch stainless steel, similar to header 12 in Figure 1, and is connected to channel section 70 by conveir tional means known to those skilled in the art, such as by welding, bolting, threading or clamping. Channel 70 comprises a flanged cylindrical shell, similar to channel 22 in Figure 1, and is constructed of inch stainless steel. The lower side of channel 70 is connected in a suitable manner to the upper portion of shell 52. Nozzle 56 is preferably inserted at the mid point in header 54 and extends into the main reaction chamber.

Membranes 58 comprise a plurality of foraminous metal membranes or screens, similar in construction to membranes 43 or 66 in the initiator chamber or metalscreens 18 in the single reaction chamber in Figure 1. Screens 58 are positioned transversely across the upper portion of the main decomposition chamber preferably at a point approximately 1 inch from the header 54. Screens 58 are supported within the main reaction chamber, or are attached to the walls of shell 52 by-convcntional means known to those skilled in the art such as by welding or bolting. The depth of screens 58 may be of any suitable thickness depending upon the capacity requirements of the reaction chamber, and while screens 58 may vary from the thickness of a single screen, it is preferred that they have a depth of at least several inches. Screens 58, 46, 48 and 66 may be of any suitable mesh and preferably a 20 to 100 mesh and of .016 inch wire. Nozzle 60, which may be an exhaust nozzle, venturi or other means for conducting gases from the main reaction chamber, is similar in construction to nozzle 20 in Figure 1. This nozzle or other outlet means is fastened to the outlet end of shell 52 by threading, welding, bolting or clamping, known to those skilled in the art, and may be made of any suitable metallic material such as stainless steel, copper, brass or iron. Numeral 72 indicates a break in the drawing and thus the apparatus is not shown in its true length. Within this main reaction zone, hydrazine decomposition takes place for the most part within the area confined by metal screens 58.

A valved-conduit 74 is attached to nozzle 44 for the introduction of hydrazine into the aforementioned initiator chamber, the rate of flow being controlled by valve 76 in conduit 74. Conventional pumping apparatus, represented by pump 78, is connected to conduit 74 for pumping a supply of hydrazine from a suitable storage vessel which is attached to pump 78 through conduit 82. Another valved-conduit84 is attached at one end to conduit 74 and is connected at the other to nozzle 56 for the purpose of introducing hydrazine into the main reaction chamber, the rate of flow being controlled by valve 86. Storage vessel 80 and conduits 82, 74 and 84 are constructed of any suitable material, similar to storage vessel 34 and conduits 36 and 28 in Figure 1, such as stainless steel or iron,

It has beenindicated'thata metal"screen=66 is positioned 1 transversely ,acrossthe base-1, of screen 46am the initiator chamber. It should be noted, however, that while it is preferableto employ thisfscree'n in the initiator chamber,

the function ofithei apparatuslmay nevertheless be. carried out successfully withoutzscreen-66 being present; It'has. also been indicated tliat screenz46is preferably a truncated conical screen. "'In =this respect'it should be -noted. thatgwhile a.truncatedconicalscreen is preferredinthe modification of the apparatus illustrated in Figure 2, other 1 forms of metal screens may. also; be successfully. em-

ployed'such as acylindricalscreen. i e I In this respect, it should benoted that wh'i meme layerstof the aforementioned catalyst particles, it isalso.

I possible: to employ a cylindricalforaminous" metal memf-'-- brane or screen,.for this purpose, positioned 'longitudinallyz-w eczema of these metals, or combinationof-j any Qneon'EtWO -Gfii these metals. with oxygen-containing compounds: of-"any one or two of the remaining-metals,v in proportions'sucm branesc161in-Figure1 have beenidescribed ascompris i ingca plurality ofmetal screens superimposed onalternate thatthese components on the metal weight basis-consist:.

of approximately 30 to 80% cobalt; 10 to.45%- copper;

and 10 to 45% of. thefalkali metal (as more. fully de, scribed in a prior and copendingapplicationSerial;No;l

76,185, filed February 12, 1949, in Which Ru'ss'ell..M;.

Mantell'and Otto J. Ple scia of the presentzinventionwerei. the co-inventors in that application); Thus 'apreferred;

;catalyst for initiating the reaction, maybe a granular; catalyst mass prepared by the ignition ofa mixturewof-a cobaltic oxide, ,cupric nitrate and sodium bicarbonate; having a composition on -a weight percent" metal basisofis approximately 57% cobalt; 2.1%. copper and/22%: so:-

*dium, The granular. catalyst mass-mayberutilized in-zthe:

vform of pellets, extrusions, wires, beads: and. the.like,::

which may have been previously activated lby'reductioni within the,reactionichamber, butl-at adistance .of approx-c imatelyz /sinch from the walls of the reaction chamber, withrthe catalyst particles positioned within the' hollow.

space formed between-shell 10 and the above-mentioned: cylindrical 'metali'screen. In another. modification ofsthez metal'sereens c'omprisingmeimbranes 16, in Figure l in the drawing; itis possibletohave the aforementioned cylindrical metal screen-positioned in an opening; running through thecenter of metal screens 16, if soj'desired. It should also be noted that screens 18 intFrigure i l an'd58.

3 with hydrogen orother suitable reducing media. 20

.(Upon contact with catalyst: 24 in-hollow spacesjZtii.v

initial decomposition'of hydrazine introduced through f From the hot gases resultingg from the aforementioned hydrazine decomposition; in hollow spaces 26, heat is suppliedv bythepassage of these;

screens 16 takes place.

gases-to screens 18. During the passage ofthese;g ases;

. a through screens 18, the screens areheated to'a tempera'-.- ture of at least about400 F. or higher; depending upona in Figure 2 mayhlso comprise a series of screens of copper wool, coils of metal j gauze; or porous; sintered:

metal disks, if SOfdeSlI'Qd; V v

Furthermore, although shells 1t), 4t and 52 inFigures.

land 2 have been described cylindrical in shape, it.

will be. noted that while suchishape' ispreferredother shapes such assphericalmay'also be successfully employed if. so desi'red- It will. alsobenotedz'that various: otheralterations and modificationjofthevarious features of the apparatus and the dimensionsthereof may be practiced by those skilledin theartwithout departing from the scope of the'invention. i

oPERATtoN In theoperation at the apparatusof the single reaction chamber modification in Figure 1 of the drawing for carrying out the catalytic, decomposition ot hydrazine as a-gas generant, hydrazineis drawn from storage vessel I 34* through conduit 36 by pumpflZ. Hydrazine thus withdrawn from'yessel 34is" introduced through atomizer nozzle 14 into the reaction chamber via valved conduit 30. Hydrazine thus introduced into the reaction chainberis preferably in -the form o' f a hydrazine-water .mjxturein the Weight ratio of approximately 421, although.

low. spaces-26 without flooding the' catalystwith co,ol3, hydrazine. liquid, therebyque'nching the decomp'ositi'onax the nature of the catalyst positionedin hollow spacesa:

26. 'In this respect, it will be noted'thatwhile hydrazine or hydrazine: hydrate can. be decomposed atz'a temperature-within the ,rangeafrom about.572-? F, to: v 7 about 662 F., we have foundfthat it is sutficienttoxpre-i .heat s'creens 18 to the aforementioned? temperature-off about 400 F. in order 'to carry out-further self-sustained. hydrazine decomposition, the scre'ensythUs actinglasxa; catalyst. .It has been indicated above that hydrazine; is introduced'into decomposition orreactiomchamberr at anvinitial fiow. rateof aPPrOXimatelyone gallonip'era; hour. "This rate of flow is necessarily low inorder to-iinitiate the hydrazine decomposition reaction within'shol However, this relatively low rate 'of;hydrazinexinjec;-2 tion needonly be maintained, for suchlength'of-itimez a'swill permit screens18'to reachthe desired temperae ture; of at least about 400? F., after which period-the rate of hydrazine injection may be increased to a rates as high as 30v gallons 'per hour or higher, screens lsfhaving been sufficiently preheated, so thatthey now servet as the principal catalyst in'decomposing "furtherquarra tities of hydr'azine at a sustainedincreased injection rate&

., 7 into the reaction chamber.

anhydrous hydrazine, orhydrazine diluted-with other.

suitablediluents; in varying proportions su'chfl fas ammoniao-rcompoundsof hydrazine-such as hydrazine hydrate,

. composition of hydrazine by preheated screens 18': build: 7 up the pressure for the most part within thesreactionii chamber and .pass through screens 18 and ourthrougha either as a gas or liquid may also besuccessfully utilized in accordance with the methodof the operation. Hy-

, draz ine is injected into the reaction chambera-t atmosphe'ric temperature through adjustable nozzle 14, pref-,-

erably inthe form of a-fine spray at an intial'flow rate; of approximately one gallon per hour, and is subsequently increased toathigher fiovv rate by proper manipulation of valve 30-in' conduit23, such asa flowrate of approxi mately 30 gallons per houror higher, in accordance Wlilh the method of operationhereinafter described.

Hydrazine thus introducedas a-spr'ay into the-reaction where itis contacted bycatalyst'24 in a'fixed-bed state; Gatalyst 24- may be any catalystwhich at atmospheric "temperatu e is efiective for'initiating the decomposition reactions Various catalysts may be employed for this purpose and preferably a catalyst prepared-fromcobalt, cop

perand'an alkali metal, or a catalyst'prepared-from elementary, cobalt; popper and an alkali metaLQor' a catalyst preparedirom" an oxygen-containing compound of-each chamber, passes through screens 16'into hollow. space1261" 'The hot decomposition products thus produced: by dee exhaust nozzle 26 at a temperature of between about: 1300? F. and about 1500".F. It is possible'to meas -ure the pressure thus created, bythe insertion of, 351K681 80 through conduit 82 by pump 78. Hydrazine thus."-

" Withdrawn from vessel 80 is introducedthrough atom- I duced into this decomposition zone is preferably in'thej izer nozzle 44 into the first reaction chamber or initiator. chamber ,via valved, conduit 74. Hydrazine thus intro- 1 form of a hydrazine-water mixture inthe, weight ratio of' approximately 4:1, although anhydrous .h'ydrazine; or. hydrazine diluted with other suitable diluentsinvary ing proportionssuchas ammonia, or compounds-0f 7. hydrazine such as hydrazine hydrate, either as a gas or liquid may also be successfully utilized in accordance with the method of the operation. Hydrazine is injected into thisreaction zone at atmospheric temperature through nozzle 44, preferably in the form of a fine spray at a flow rate of-approximately one gallon per hour. This rate of flow, however, is not critical inasmuch'as the introduction of hydrazine into the initiator reaction zone is only for the purpose of starting up hydrazine decomposition in order to utilize the decomposition products for preheating the screen catalyst, represented by numeral 58 in the main reaction zone, as more fully hereinafter described. Hydrazine introduced as a spray into the initiator chamber passes through screens 66 and 46 into hollow space 62' where it is con tacted by catalyst 64 in a fixed-bed state. Catalyst 64 may be any catalyst which at atmospheric tempera-. ture is elfective for initiating the decomposition reac-" tion. Various catalysts may; therefore, be employed for this purpose, with catalysts such as described" in themodification of the apparatus illustrated in Figure 1 being preferred. Upon contact with catalyst 64 in hollow space 62 initial decomposition of hydrazine introduced through screens 66 and 46 takes place. The hot gases resulting from the aforementioned hydrazine decomposition in hollow space 62 next pass screen 48 into the main reaction chamber, via conduit 50. As

' a result of the passage of these hot gases through conduit 50 into the main reaction chamber, screens 58 are heated to a temperature of at least about 400 F. or higher, depending upon the nature of the catalyst positioned in hollow space 62 in the initiator chamber. When screens 58 have been heated to the aforementioned temperature of at least about 400 R, an increased rate of hydrazine is next introduced through adjustable atomizer nozzle 56 into the main reaction zone, and the hydrazine decomposition reaction then becomes self-sustained. Hydrazine thus utilized for this purpose in the main reaction zone is supplied through valvedconduit 84 which is attached at one end to nozzle 56 and is connected at the other end to conduit 74 for pumping a continuous supply of hydrazine from storage vessel 80; Once the reaction in the main reaction zone has become self-sustaining following a sufficient preheating ofscreens 58, shut-ofi valve 76 in conduit 74 may be entirely closed, thus cutting off the further generation of hot gases from the initiator chamber which were previously supplied to the main reaction zone through conduit 50. Thereupon, valve 86 in conduit 84 may be so adjusted as to increase the rate of flow of hydrazine into the main reaction chamber, to a rate such as about 30 gallons per hour or higher. It will be understood that in thestarting-up decomposition reaction in the initiator zone, valve '86 remains closed until such'tirne as screens 58 have been brought up to the proper temperature sufficient for carrying on further hydrazine decomposition on a-self-sustaining basis. When screens 58 have been preheated by the hot decomposition gases from the initiator chamber, valve 76 in conduit 74 is desired to measure the pressure thus created in the main reaction zone by the insertion of one or more pressure taps at, any point along the length of shell 52 and extending into the reaction zone, but which is not shown in the drawing.

' The following examples are ofiered as a means for a better understanding of the invention and should not be construed as unnecessarily limiting to the. invention.

EXAMPLE I I of the chamber a pressure tap was also inserted. Thermocouples were inserted into the top, bottom and middle portions of the chamber. A series of circular brass screens having a total thickness of 6 inches, a 20 mesh and made of .016 inch wire was positioned transversely across the upper portion of the initiator chamber at a distance of 1 inch from the top of the shell, and served as screens 16 in Figure l in the drawing. A granular mass prepared by the ignition of a mixture ofcobaltic oxide, cupric nitrate and sodium bicarbonate having a composition on a weight percent metal basis of approximately 57% cobalt, 21% copper and 22% sodium was pelleted and employed as catalyst 24 in hollow space 26 between alternate layers of brass screens 16. Another series of superimposed circular brass screens having a total thickness of V2. inch was positioned transversely across the outlet end of the reaction chamber, similar in construction to screens 16 and served as screens 18 in Figure 1 in the drawing. An aqueous solution containing approximately hydrazine was fed into this reaction chamber through atomizer nozzle 14 and the resulting chamber temperatures and pressures were recorded from a series of runs as given in Table I below:

Table I Chamber Temperatures, F. Chamber Fuel Flow, lb./sec. Pressure (p.s.i.a.) Top Middle Bottom EXAMPLE II chamber, as in Figure'2 in the drawing, consisted of a cylindrical stainless steel pipe approximately 4 inches in length with an inside diameter of approximately 1% inches. Screen 46 in this initiator chamber was an 80 degree truncated conical brass screen employed as a retaining membrane together with brass screens 66 and 48 positioned across the inlet end and outlet ends, respectively. A granular catalyst having a composition similar to the catalyst employed in the method and apparatus in Example I was positioned in hollow space 62 between the walls of the initiator chamber and brass screen 46. Hydrazine at an initial flow rate of approximately one gallon per hour was introduced through nozzle 44 in the initiator chamber. The resulting hot decomposition products from the initiator chamber were permitted to pass into the main reaction chamber. The main reaction chamber consisted of a stainless steel pipe approximately 10% inches in length and having an inside diameter of approximately 3 inches with a series of superimposed circular brass screens having a total thick- 75 ness of 2 inches, and similar to brass screens 18 in the the main reaction chamber. serted into *the top, bottom and middle portions of the main reaction chamber,-and a pressure tap was inserted near the end of this chamber. At the end of this reaction as screens 58 in Figure 2 in the drawing, was positionedreaction-chamber-of Figure 1 inthe drawing, andser ving transversely across the upper portion of the main decomposition chamber at apoint approximately 1 inch below the point of introduction of. the hot decomposition gases from the initiator chamber. When screens 58 had been preheatedto approximately 400 F; the flow of hydrazine into the initiator chamber was cut off and hydrazine was then introduced through nozzle 56 "into Thermocouples were in-- chamber was. attached a A; inch exhaust nozzle. The

resulting chamber temperatures and pressures in the mainreaction chamber were recorded from a series of runsas given in, Table 11- below:

7. The processof claim 2' wherein said second catalyst comprises a copper screen.

t "8. The process of claim 2 wherein said second catalyst comprises an iron screen..

'9. A method for decomposing hydrazine which comprises: contacting hydrazine in a first reaction zone with a catalyst, which at a relativelylow temperature is eflective for initiating the decomposition reaction, whereby at least a portion of said hydrazine is decomposed with the liberation of heat; exposing in a second reaction zonea second catalyst, comprising'a forarninous metal-membrane composed of a material selected from the group consisting of brass, copper, iron" and steel, to the heat t of decomposition liberated by contact of hydrazine withsaid first catalyst'to preheat said second catalyst to a,

temperature effective to promote the decomposition of" hydrazine; and contacting the thus heated second catalyst with further quantities of hydrazine to elfectdecomposi- Having thus described, our invention, we claim:

prises: contacting hydrazine with a catalyst, whichat a,

rela'tiyely low temperature is efiective for initiating'the,

decomposition reaction, whereby. at least a portion of said hydrazine is decomposed with the liberation of heat; ex-

4 posinga second catalyst, comprising a foraminous metal,

membrane composed of a material selected from the heat of decomposition liberated by contact of hydrazine with said first catalysttoj preheat said second catalyst to a temperature effective to promote the decomposition of withfurther quantities of hydrazine to effect decomposition thereof.

to a temperature eifec tive to promotethe decomposition oh hydrazine; and contacting the this heated second catalyst with further quantities of hydrazine to effect decomposition thereofa 3.'The process of claim ZWherein and an alkali metal.

4. The processof chiral/wherein said first catalyst comprises an efiective, amount of each of ,ametallic; co-

baltand an oxide of each of copper and an alkaliimetal in proportions such that these components of: thecatalyst on the metal weight "basisconsist-of approximately -80% cobalt, 10-45% copperand 10-45% alkali metal. i i

5. The process of claim 2 wherein said first catalyst 1 A" method for decomposing hydrazine which comtion thereof. q I I c p 10. A method for decomposing hydrazine which comprises: cont-acting hydrazine'in a first reaction zone with a catalyst, which at a relatively low temperature 'is effectit e for initiating the decomposition reaction, whereby at least. a portion of said hydrazine'is decomposed with the'liberationofheat; passing the resulting heated decomposition products from con-tactwith said first catalyst; in saidfirst reaction. zone through a second reaction zone in contact with a second catalyst, comprising a foraminous .metal membrane composed of a material selected 6 from the group consisting of brass, copper, iron and a steel, to preheat. said second catalyst tov a temperature effective to promote the decomposition of hydrazinerand contacting the thus heated second catalyst with further I quantities of hydrazine to effect decomposition thereof.

1,1. Amethod for decomposing hydrazine which com.-

, prises; contacting hydrazinein a first reaction zone with.

'- group consisting 'of'brass, copper, iron and steel,',to the hydrazine; and contacting the thus heated second catalyst a catalyst, whichfat atmospheric temperature iseifective for initiating the decomposition reaction, whereby at least aportion. of saidhydrazine is decomposed with the liberaa.

"tion of hea'tjpassing the resulting heated decomposition productsfrom, contact with said first catalyst in said firstjreaction. zone through a second reaction zone in contact with a second catalyst, comprising a foraminous.

. method for decomposing hydrazine h j metal membrane composed of a material selected from prises?contacting hydrazine with a catalyst which; ata

the groupconsisting tof brass, copper, ironand steel, to preheat said second catalyst to atemperature of at leastabout 400 F: to promote the-decomposition of "hydra'zine; and contacting the thus heated second catalyst;

. with furtherqua'ntities'of hydrazine to effect decomposition thereofi v v 12'. A methodtfordecomposing-hydrazine which'com-r prises: contactinghydrazinein a; first reaction zone-witha catalyst, comprising an effective amount of cobaltic,

said first catalyst comprises an efiective amount of each offcobalt, copper oxideQcupric nitrate, and sodium'bicarbonate in. proportions such that components of the catalyst on the metal.

from-,the group consisting of brass, coppen'iron and'steel.

comprises an effective amount of an'oxide of each of cobalt, copper and an alkali metal in proportions such that these components of the catalyst on the metal weight basis consist of approximately 30-80% colbalt, ,10-45% copperjand 10-45% alkali metal.

6. The process of claim 2 wherein said second catalyst comprises a brass screen. t

to preheattsaid second catalyst to a temperature of at leastabout 400- F. to promote the decomposition of hydrazine; contacting the .thus heated second catalyst With;further quantities of hydrazine to eifect decomposition thereof; and subsequently discontinuing the flow of hydrazine over .said first catalyst, but continuing thev flow of hydrazine over said second catalyst. which is at a sufficiently high temperature to decompose hydrazine Without preheating.

13. The process of claim 2 wherein said firstcatalyst comprises an efiective amount of cobaltic oxide, cupric nitrate and sodium bicarbonate in proportionssuch that these components of the catalyst on the metal weight basis consist of approximately 30-80% cobalt, -45% copper and 10-45% sodium.

14. The process of claim 2wherein said first catalyst comprises an effective amount of cobaltic oxide, cupric nitrate and sodium bicarbonate in proportions such that these components of the catalyst on the metal weight basis consist of approximately 57% cobalt, 21% copper and 22% sodium.

15. Apparatus for the decomposition of hydrazine, which comprises in combination: an elongated cylindrical first reaction chamber; a cylindrical metal screen positioned longitudinally within said first reaction chamber, forming a hollow space between the walls of said first reaction chamber and said metal screen, adapted to contain a granular catalyst disposed in said hollow space; means for introducing hydrazine into one end of said first reaction chamber within the enclosure formed by said metal screen; a second metal screen positioned transversely, across one end of said first reaction chamber; an elongated cylindrical second reaction chamber; a third metal screen positioned transversely across' said second reaction chamber; a conduit communicating with one end of said first reaction chamber and one end of said second reaction chamber; means for introducing hydrazine into said second reaction chamber; and means for withdrawing products of reaction from said second reaction chamber. I

16. Apparatus for the decomposition ofhydrazine, whiclrcomprises in combination: an elongated cylindrical first reaction chamber; a truncated conical metal screen positioned longitudinally, within said first reaction chamber, forming a hollow space between the walls of said first reaction chamber and said metal screen, adapt ed to contain a granular catalyst disposed in said hollow space; means for introducing hydrazine into one end of said first reaction chamber within the enclosureformed by said metal screen; a second metal screen positioned transversely, across one end of said first reaction chamber; an elongated cylindrical second reaction chamber; a third metal screen positioned transversely ,across said second reaction chamber; a conduit communicating with one end of said first reaction chamber and one end of said second reaction chamber; means for introducing hydrazine into said second reaction chamber; and means for withdrawing products of reaction from said second reaction chamber.

"17. Apparatus for the decomposition of hydrazine, which comprises in combination: an elongated cylindrical first reaction chamber; a truncated conical metal screen positioned longitudinally within said first reaction chamber, forming a hollow space between the walls of said first reaction chamber and said metal screen, adapted to contain a granular catalyst disposed in said hollow space; a nozzle for spraying hydrazine into one end of said first reaction chamber within the enclosure formed by said truncated conical metal screen; a second metal screen positioned transversely, across one end of said first reaction chamber; an elongated cylindrical second reaction chamber; a third metal screen positioned transversely across said second reaction chamber; a conduit communicating with one end of said first reaction chamber and one end of said second reaction-chamber; a nozzle for spraying hydrazine into said second reaction chamber; and means for withdrawing products of reaction from said second reaction chamber. I

. 18. Apparatus for the decomposition of hydrazine,

'12 which comprises in combination: an elongated cylindrical first reaction chamber; a first metal screen positioned transversely across one end of said first reaction chamber; a truncated conical second metal screen positioned longitudinally within said first reaction chamber forming a hollow space between the walls of said first reaction chamber and said second metal screen, adapted to contain a granular catalyst disposed in said hollow space; a nozzle for introducing hydrazine into one end of said first reaction chamber within the enclosure formed by said truncated conical metal screen; a third metal screen positioned transversely across the other end of said first reaction chamber; an elongated cylindrical second reaction chamber; a fourth metal screen positioned transversely across said second reaction chamber; a conduit communicating with one end of said first reaction cham-- ber and one end of said second reaction chamber; a nozzle for spraying hydrazine into said second reaction chamber; and means for withdrawing products of reaction from said second reaction chamber.

19. A method for decomposing hydrazine which comprises: contacting hydrazine with a catalyst, which at a relatively low temperature is elfective for initiating the decomposition reaction, whereby at least a portion of said hydrazine is decomposed with the liberation of heat; exposing a second catalyst, comprising a foraminous metal membrane composed of a material selected from the group consisting of brass, copper, iron and steel, to the heat of decomposition liberated by contact of hydrazine with said first catalyst to preheat said second catalyst to a temperature of at least about 400 to promote the decomposition of hydrazine; and contacting the thus heated second catalyst with further quantities of hydra- Zinc to eifect decomposition thereof.

20. A method for decomposing hydrazine which comprises: contacting hydrazine with a catalyst, which at a relatively low temperature is efiective for initiating the decomposition reaction, whereby at least. a portion of said hydrazine is decomposed with the liberation of heat; passing the resulting heated decomposition products from contact with said first catalyst over a second catalyst,

comprising a foraminous metal membrance composed of a material selected from the group consisting of brass,

' copper, iron and steel, to preheat said second catalyst to a temperature of at least about 400 F. to promote the decomposition of hydrazine; and contacting the thus heated second catalyst with further quantities of hydra zine to efiect decomposition thereof.

References Cited in the file of this patent UNITED STATES PATENTS 723,595 Ferguson Mar. 24, 1903 1,036,473 Eschellmann et al. Aug. 20, 1912 2,178,833 Erasmus Nov. 7, 1939' 2,220,849 7 Riblett Nov. 5, 1940 2,276,229 Dixon Mar. 10, 1942 OTHER REFERENCES (Copy in Scientific Library.)

Chemical Abstracts, vol. 34, Jan.-Mar., 1940, col. 314

(2), Decomposition of Hydrazine by Raney Nickel. (Copy in Scientific Library.) 

